1. B.o.B. – Bobby Ray dropped several crunk-filled mixtapes before releasing his first official album.  When the album dropped, however, it was filled with lots of pop, rock and just a little bit of crunk…and it was dope.  In addition to garnering 5 Grammy nominations, including Record of the Year, he also helped to launch the career of label mate Bruno Mars.  He capped off the year with a mixtape called No Genre to further underscore his diversity in music.  Here are a couple of tracks that show off his range (please pardon any annoying messages on the video “embeds” directing you to YouTube):

2.  KiD CuDi – CuDi has been stretching hip-hop boundaries for a minute now and 2010 was no different.  This year he took things to a different level, adding rock to his “emo rap” repertoire, and he even got Kanye to rock out with him.

3.  Cee-Lo – Cee-Lo Green has not done straight hip-hop for a LONG time.  But since his roots lie with Outkast and The Goodie M.O.B. he will always be a part of the hip-hop family which, luckily, means we get to claim all the fruits of his prodigious talent.  In 2010, he made one of the catchiest, dirtiest songs of all time and also one of the coolest videos in years, both of which stretched the definition of “hip-hop”:

4.  Nicki Minaj – Nicki Minaj was one of the biggest artists of 2010.  Period.  She will soon be the first woman rapper (not named Missy Elliott) to go platinum since Lauryn Hill…and that was in 1998.  There will be more on Nicki later in this series (hint, hint) but for now, here is a great video to show how she pushed boundaries:

As with reason #10 for why 2010 is the greatest year ever for hip-hop (several great comebacks), this is not meant to be comprehensive but simply a reminder of just how much the boundaries of hip-hop were pushed in 2010.  No disrespect to Yelawolf, Kanye (who could be in all of these reasons), and others who helped to expand the culture.  Their presence was greatly felt and all contributed to a helluva year.